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Building Tips and technical articles. => Paint and finishing => Topic started by: Tim Wescott on June 06, 2010, 05:18:47 PM

Title: Minwax Poly What???
Post by: Tim Wescott on June 06, 2010, 05:18:47 PM
I was in Home Despot today, getting keys made, when I thought I'd swing by the paint section and maybe pick up some of that Minwax stuff I've been hearing about.

Oh, the tragedy of today's indecisive consumer!  There's Minwax Polycrylic, Minwax Polyurethane (quick dry!) in three different finishes (flat, satin and gloss), "Huntsman spar varnish" (apparently made by Minwax) as well as a bunch of different colored stuff.

I reeled out of there and got my keys, emitting only a faint moan at the selections of multi-colored keys that are possible these days.

So -- do I _really_ want the Minwax Polycrylic, which is water based, is what I think everyone recommends, and which will chance warping up my nice straight fuselage?  Or do I want to get Minwax Polyurethane, which is oil-based, quick dry(!) and comes in smaller cans for the timid tryer out of new stuff?

Or should I just get a gallon of Sig Lite-Coat and sort through my 30 year old Silkspan collection?
Title: Re: Minwax Poly What???
Post by: Steve Helmick on June 06, 2010, 06:01:45 PM
Don't buy the colored keys...they're aluminum, and are more likely to twist off in a reluctant lock. Brass is good!

As for the various finishing products, the PolyCrylic is neat stuff for some uses. It's compatible with just about anything (your MPG may vary!), but it's not fuel proof.

Butyrate dope is generally light, repairable and with pretty good fuel resistance. Clear dope is very light, except the first coat. A little pigmented dope mixed with clear is a nice option. Doesn't fade like dye, and not as heavy as regular pigmented dope. Needs spraying, tho.  H^^ Steve
Title: Re: Minwax Poly What???
Post by: Gene O'Keefe on June 06, 2010, 06:13:45 PM
Buy the Sig Lite-coat & find your best silkspan and forget the Polycrylic

 Geno
Title: Re: Minwax Poly What???
Post by: ray copeland on June 06, 2010, 08:58:53 PM
Tim, i have used the gloss quick dry polyurethane on 6 or 8 planes now as a topcoat to fuel proof and love it, even better than the duplicolor acrylic enamel clear. Beware it will yellow some over white. I have only used the spray cans but i do plan to buy the quart can and brush on sometime.
Title: Re: Minwax Poly What???
Post by: Tim Wescott on June 06, 2010, 10:53:08 PM
Tim, i have used the gloss quick dry polyurethane on 6 or 8 planes now as a topcoat to fuel proof and love it, even better than the duplicolor acrylic enamel clear. Beware it will yellow some over white. I have only used the spray cans but i do plan to buy the quart can and brush on sometime.
Do you know how it does under Rustoleum?  I'm planning on film covering for the wings and empennage, Rustoleum on the fuselage, and Rustoleum trim everywhere.

The plane will be screaming bright yellow, so maybe I'll overcoat it, although dull yellow probably shows on screaming bright yellow.
Title: Re: Minwax Poly What???
Post by: philip metzner on June 07, 2010, 03:19:13 AM
Tim, when i started looking in to this i got confused by which product to use. What i ended up with is minwax oil based polyurethane gloss. On the planes i have built or finished lately i was interested in fast and cheep finishes. I have been monocoating the wing and using the poly on the rest. The only paint i used over the poly so far was aerogloss dope. The poly had dried for a couple weeks and i brushed the color dope on. It was ify but it worked. It probably wouldnt have if i had thinner in the dope. I have an idea that the rustolium would work fine.
Title: Re: Minwax Poly What???
Post by: phil c on June 09, 2010, 02:27:12 PM
Varathane and CarverTripp are two brands of water-based varnish that are pretty fuel proof.

Don't use w-b urethane on silkspan over open bays.  It will get brittle as hell.  Works fine over wood foam though.

If you are still hell bent on silkspan, it is a good idea to apply plastic film over the open bays first to protect against dents and tears.  The good old Russians first started doing this 30 years ago.  It works.